// SPDX-License-Identifier: GPL-2.0
#include "vkms_drv.h"
#include <linux/crc32.h>
#include <drm/drm_gem_framebuffer_helper.h>

static uint32_t _vkms_get_crc(struct vkms_crc_data *crc_data)
{
	struct drm_framebuffer *fb = &crc_data->fb;
	struct drm_gem_object *gem_obj = drm_gem_fb_get_obj(fb, 0);
	struct vkms_gem_object *vkms_obj = drm_gem_to_vkms_gem(gem_obj);
	u32 crc = 0;
	int i = 0;
	unsigned int x = crc_data->src.x1 >> 16;
	unsigned int y = crc_data->src.y1 >> 16;
	unsigned int height = drm_rect_height(&crc_data->src) >> 16;
	unsigned int width = drm_rect_width(&crc_data->src) >> 16;
	unsigned int cpp = fb->format->cpp[0];
	unsigned int src_offset;
	unsigned int size_byte = width * cpp;
	void *vaddr;

	mutex_lock(&vkms_obj->pages_lock);
	vaddr = vkms_obj->vaddr;
	if (WARN_ON(!vaddr))
		goto out;

	for (i = y; i < y + height; i++) {
		src_offset = fb->offsets[0] + (i * fb->pitches[0]) + (x * cpp);
		crc = crc32_le(crc, vaddr + src_offset, size_byte);
	}

out:
	mutex_unlock(&vkms_obj->pages_lock);
	return crc;
}

/**
 * vkms_crc_work_handle - ordered work_struct to compute CRC
 *
 * @work: work_struct
 *
 * Work handler for computing CRCs. work_struct scheduled in
 * an ordered workqueue that's periodically scheduled to run by
 * _vblank_handle() and flushed at vkms_atomic_crtc_destroy_state().
 */
void vkms_crc_work_handle(struct work_struct *work)
{
	struct vkms_crtc_state *crtc_state = container_of(work,
						struct vkms_crtc_state,
						crc_work);
	struct drm_crtc *crtc = crtc_state->base.crtc;
	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
	struct vkms_device *vdev = container_of(out, struct vkms_device,
						output);
	struct vkms_crc_data *primary_crc = NULL;
	struct drm_plane *plane;
	u32 crc32 = 0;
	u64 frame_start, frame_end;
	unsigned long flags;

	spin_lock_irqsave(&out->state_lock, flags);
	frame_start = crtc_state->frame_start;
	frame_end = crtc_state->frame_end;
	spin_unlock_irqrestore(&out->state_lock, flags);

	/* _vblank_handle() hasn't updated frame_start yet */
	if (!frame_start || frame_start == frame_end)
		goto out;

	drm_for_each_plane(plane, &vdev->drm) {
		struct vkms_plane_state *vplane_state;
		struct vkms_crc_data *crc_data;

		vplane_state = to_vkms_plane_state(plane->state);
		crc_data = vplane_state->crc_data;

		if (drm_framebuffer_read_refcount(&crc_data->fb) == 0)
			continue;

		if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
			primary_crc = crc_data;
			break;
		}
	}

	if (primary_crc)
		crc32 = _vkms_get_crc(primary_crc);

	frame_end = drm_crtc_accurate_vblank_count(crtc);

	/* queue_work can fail to schedule crc_work; add crc for
	 * missing frames
	 */
	while (frame_start <= frame_end)
		drm_crtc_add_crc_entry(crtc, true, frame_start++, &crc32);

out:
	/* to avoid using the same value for frame number again */
	spin_lock_irqsave(&out->state_lock, flags);
	crtc_state->frame_end = frame_end;
	crtc_state->frame_start = 0;
	spin_unlock_irqrestore(&out->state_lock, flags);
}

static int vkms_crc_parse_source(const char *src_name, bool *enabled)
{
	int ret = 0;

	if (!src_name) {
		*enabled = false;
	} else if (strcmp(src_name, "auto") == 0) {
		*enabled = true;
	} else {
		*enabled = false;
		ret = -EINVAL;
	}

	return ret;
}

int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
			   size_t *values_cnt)
{
	bool enabled;

	if (vkms_crc_parse_source(src_name, &enabled) < 0) {
		DRM_DEBUG_DRIVER("unknown source %s\n", src_name);
		return -EINVAL;
	}

	*values_cnt = 1;

	return 0;
}

int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
{
	struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
	bool enabled = false;
	unsigned long flags;
	int ret = 0;

	ret = vkms_crc_parse_source(src_name, &enabled);

	/* make sure nothing is scheduled on crtc workq */
	flush_workqueue(out->crc_workq);

	spin_lock_irqsave(&out->lock, flags);
	out->crc_enabled = enabled;
	spin_unlock_irqrestore(&out->lock, flags);

	return ret;
}